Gary Stuart Sandlin, 83, of Longmont, Colorado passed away on January 5, 2017, at St Anthony's North Hospital, Westminster, Colorado. He was born June 10, 1933, in Palco, Kansas, to Edwin Sandlin and Mary Rachael (Dorman) Sandlin. He graduated from Hill City Memorial High School, in 1951, and went on to earn a Bachelors and Masters degree in Geology from Kansas State University. Gary worked as a geologist in Casper, Wyoming and Albuquerque, New Mexico, before becoming an independent geologist in Denver, Colorado. He was the Owner and President of Sandlin Oil Corporation. Gary enjoyed hunting, fishing, horseback riding, playing his guitar, loved his profession of geology, and was an avid reader. Gary is survived by his wife, Kathie Sandlin, daughter, Laura Rodriguez Sandlin and her husband, Paul Rodriguez, stepson, Billy Kimbrough, Sister, Karen Summers, Brother, Steve Sandlin, and his wife, Cathy, many nieces and nephews, previous wife Betty Keiswetter Higbie and her husband, Lee. Gary is preceded in death by his parents, Edwin and Mary (Dorman), Sandlin, son, Jeff Sandlin, brother, Arlen Sandlin, brother, Curtis Sandlin. A Celebration of Gary's Life will be held Saturday, January 28, 2017, 11 AM, Rinn United Methodist Church, 3783 Bella Rosa Parkway, Longmont, CO 80504. (WCR 20 & I-25 Frontage Road) In lieu of flowers, memorial may be given to the Salvation Army, c/o Donations, 1300 Pennsylvania Street, Denver, CO, 80203, or to the Gary and Kathie Sandlin Geology Scholarship, Kansas State Foundation, 1800 Kimball Avenue, Suite 200, Manhattan, KS, 66502-3373.